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Can Exercise Keep You Young?

By Gretchen Reynolds March 2, 2011 12:02 amMarch 2, 2011 12:02 am

We all know that physical activity is beneficial in countless ways, but even so, Dr. Mark Tarnopolsky, a professor of pediatrics at McMaster University in Hamilton, Ontario, was startled to discover that exercise kept a strain of mice from becoming gray prematurely.

In the experiment, Dr. Tarnopolsky and his colleagues used lab rodents that carry a genetic mutation affecting how well their bodies repair malfunctioning mitochondria, which are tiny organelles within cells. Mitochondria combine oxygen and nutrients to create fuel for the cells — they are microscopic power generators.

Mitochrondria have their own DNA, distinct from the cell’s own genetic material, and they multiply on their own. But in the process, mitochondria can accumulate small genetic mutations, which under normal circumstances are corrected by specialized repair systems within the cell. Over time, as we age, the number of mutations begins to outstrip the system’s ability to make repairs, and mitochondria start malfunctioning and dying.

Many scientists consider the loss of healthy mitochondria to be an important underlying cause of aging in mammals. As resident mitochondria falter, the cells they fuel wither or die. Muscles shrink, brain volume drops, hair falls out or loses its pigmentation, and soon enough we are, in appearance and beneath the surface, old.

The mice that Dr. Tarnopolsky and his colleagues used lacked the primary mitochondrial repair mechanism, so they developed malfunctioning mitochondria early in their lives, as early as 3 months of age, the human equivalent of age 20. By the time they reached 8 months, or their early 60s in human terms, the animals were extremely frail and decrepit, with spindly muscles, shrunken brains, enlarged hearts, shriveled gonads and patchy, graying fur. Listless, they barely moved around their cages. All were dead before reaching a year of age.

Except the mice that exercised.

Half of the mice were allowed to run on a wheel for 45 minutes three times a week, beginning at 3 months. These rodent runners were required to maintain a fairly brisk pace, Dr. Tarnopolsky said: “It was about like a person running a 50- or 55-minute 10K.” (A 10K race is 6.2 miles.) The mice continued this regimen for five months.

At 8 months, when their sedentary lab mates were bald, frail and dying, the running rats remained youthful. They had full pelts of dark fur, no salt-and-pepper shadings. They also had maintained almost all of their muscle mass and brain volume. Their gonads were normal, as were their hearts. They could balance on narrow rods, the showoffs.

But perhaps most remarkable, although they still harbored the mutation that should have affected mitochondrial repair, they had more mitochondria over all and far fewer with mutations than the sedentary mice had. At 1 year, none of the exercising mice had died of natural causes. (Some were sacrificed to compare their cellular health to that of the unexercised mice, all of whom were, by that age, dead.)

The researchers were surprised by the magnitude of the impact that exercise had on the animals’ aging process, Dr. Tarnopolsky said. He and his colleagues had expected to find that exercise would affect mitochondrial health in muscles, including the heart, since past research had shown a connection. They had not expected that it would affect every tissue and bodily system studied.

Other studies, including a number from Dr. Tarnopolsky’s own lab, have also found that exercise affects the course of aging, but none has shown such a comprehensive effect. And precisely how exercise alters the aging process remains unknown. In this experiment, running resulted in an upsurge in the rodents’ production of a protein known as PGC-1alpha, which regulates genes involved in metabolism and energy creation, including mitochondrial function. Exercise also sparked the repair of malfunctioning mitochondria through a mechanism outside the known repair pathway; in these mutant mice, that pathway didn’t exist, but their mitochondria were nonetheless being repaired.

Dr. Tarnopolsky is currently overseeing a number of experiments that he expects will help to elucidate the specific physiological mechanisms. But for now, he said, the lesson of his experiment and dozens like it is unambiguous. “Exercise alters the course of aging,” he said.

Although in this experiment, the activity was aerobic and strenuous, Dr. Tarnopolsky is not convinced that either is absolutely necessary for benefits. Studies of older humans have shown that weightlifting can improve mitochondrial health, he said, as can moderate endurance exercise. Although there is probably a threshold amount of exercise that is necessary to affect physiological aging, Dr. Tarnopolsky said, “anything is better than nothing.” If you haven’t been active in the past, he continued, start walking five minutes a day, then begin to increase your activity level.

The potential benefits have attractions even for the young. While Dr. Tarnopolsky, a lifelong athlete, noted with satisfaction that active, aged mice kept their hair, his younger graduate students were far more interested in the animals’ robust gonads. Their testicles and ovaries hadn’t shrunk, unlike those of sedentary elderly mice.

Dr. Tarnopolsky’s students were impressed. “I think they all exercise now,” he said.

Great summary of some important and interesting research. This dovetails nicely with a spate or findings in the last year about the benefits of exercise on brain health.

While it has been clear for some time that staying active can help control hypertension, diabetes, obesity, and high cholesterol, all of which can impair cognition if left unchecked, some of the more recent findings suggest a more direct link between physical activity and a healthy brain. We discuss such daily news items and their practical meaning at the Brain Today blog: http://www.BrainToday.com

Although its great to hear additional evidence that exercise can keep mice (and perhaps us) physically young, I still like to focus on the immediate rush I feel after an intense ride or run, and to savor the good mood I carry the rest of the day.

This is fairly easily observed in humans as well. Look at everyone over the age of 40 who exercises regularly and vigorously, and look at those who don’t. I dare you to not see a difference in apparent age.

Being young is more a matter of how the individual feels.
At age 56 I can say openly that my body is definately no longer young even though I am persistant in doing gym at least 3 times a week.
Yes, I’m in good shape and able to perform physical work and go for distances, but my reaction speed got worse and also the tendency to get tired is increased.
But the main thing is the feeling: a healthy mind in a healthy body.http://www.lifestyle-after50.com/fitness.html

Intriguing article. How much exercise would be needed, I wonder, to turn my silver hair back to rich brown? Or knees to about age 26 instead of 64? Exercise is good – but is there something about the intensity here that may have made the huge difference in mitochondrial changes? When one sees pictures of remarkable human beings who exercise – there was a recent clip showing on tv about a 90 plus woman who runs. She was in absolutely great shape for someone 90 plus. But she did not look like a fit 40 year old, or 60 yr old or 70 yr old.
So – we need to know more about these little mice!

But until we make exercise “easy and convenient”, most americans will still choose not to do it. Maybe we should make cell phones that weigh 15 lbs, with buttons that take lbs of force to push. Or couches that are made like exercise bikes and force you to pedal before the TV will turn on. Maybe the people who deliver the diet food to your door cuz you are so overburdened to cook should double as exercise trainers. You cant take delivery until you “drop and give me 20″. Cars with vibrating seats that will melt away the pounds with no effort, maybe? Remember, everything is SO HARD nowadays that its impossible for people to do this on their own. Dont get me started on the kids……….

I’m extremely interested in knowing more about the mysterious, exercise-mediated mitochondrial repair pathway. If this pathway exists in humans, studies involving human subjects using various forms of exercise and at different intensity levels could help tease out what sorts of exercise are most useful, from an anti-aging standpoint. My guess? A balance of strenuous cardiovascular exercise combined with intense, relatively brief strength training sessions. After all, muscle mass is such a valuable resource, especially as one gets older. Aerobic exercise alone will not do the trick.

Mitochondria, as a result of adaptation to exercise, can increase in number. This helps provide the much needed increase in oxygenated blood to working muscles. Is it possible the mice, despite the mutation, made more mitochondria anyway?
The thing I like most from the article is the recommendations from the researcher: just exercise. Start with whatever you can do. Whether that’s all you have time for or it’s all you can physically handle. Getting the habit of exercise will help a person stickl with it. For most people they think a lot has to happen right away or else their motivation declines rapidly. Begin with what you can and get into the habit. You will be less likely to talk yourself out of it then.
#4 @ 50plussam I am sorry to hear you have not progressed at all from your program. In 20 years of professional training I have never seen that happen once. I have clients that started in their 60’s and 70’s and they all improved in cardio intensity and endurance, strength and balance. I find it rather strange to hear your results.http://www.visionswellness.com

If you have a tv you can exercise. I was a gym rat off and on but I hated the trek. So I now have a robust collection of exercise DVDs and a Nordic Track, all of which take up minimal room. You don’t even have to buy the DVD if you have Netflix. I now have a favorite video trainer — I have learned about kettle bells and exercise balls and whatnot. I still like to hike and go for long walks, and maybe when I am kid free I will go back to the gym, or better yet, start fencing again, but day in and day out, most people could add 20-30 minutes of exercise to their routine if they want to.

Atul Gawande wrote a terrific article for the New Yorker a few years ago about how we age, and the “back-up” systems in our bodies (like a power plant) that step in to continue the work of genes as they begin to die. I’ve been running since the 70s (started when I was my in late 30s) and my hair is still red w/very little grey and still growing, unlike many of my friends. I always thought I possessed a mutant gene for hair color, but now it’s apparent that the mutant gene + exercise = longevity and red hair! Good article, thanks.

Interesting study. Although I’m going to have to agree with Robert. To convince people to exercise, it’s going to take an emphasis on the instant positive benefits of exercise to make people realize why it’s so great. Like that wonderful runner’s high you get after a great run.

The effects of exercise on purposefully-genetically-defective mice probably has zero relation to effects of similar exercise on normal human beings.

Some portion of the human race has been working dawn to dusk for untold centuries, certainly enough to be considered strenuous. If it changed the course of aging, it would be obvious – physical laborers would have long lives and their more sedentary managers shorter lives. That relationship does not appear in the population.

Thus, this statement from Dr. Tarnopolsky:

But for now, he said, the lesson of his experiment and dozens like it is unambiguous. “Exercise alters the course of aging,” he said.

appears to be falsified by reality. Dr. Tarnopolsky seems to have been lured into making claims and drawing conclusions that far exceed the actual results of his work. This experiment may tell us something interesting about genetically altered mice and their mitochondrial functions and the effects of exercise on them, but that’s the limit of gained knowledge.

I’m a believer! I’m 42 and have exercised regularly (1 – 1.5 hrs, 2 – 3 times a week). People routinely take me for being 10 – 15 years younger than I really am.

It’s been something of a disadvantage at work, because when I audit people and challenge them about their practices or behaviours, they presume from my looks that I’m too wet behind the ears to know what I’m talking about, when in reality I have 20 years’ experience in my field.

The upside is that by being this fit and healthy I have some hope of keeping up with my 3 and 6 year old sons. Not sure how well I’d cope with them if I had the ailments of an ‘old’ 42 year old.

I agree with Michael, you can definitely see the difference in people who exercise regularly. My partner, who is a year younger than me and extremely sedentary, looks at least 10 years older. It is really difficult to get someone who is accustomed to a lifetime of sloth to get moving, however.

We are all aging by definition simply with the passage of time beginning at the moment of conception. It seems more accurate, then, to cease use of the word “aging” when, in fact, we mean being sedentary or deteriorating because of a lack of exercise. That way, “aging” can assume its true meaning of being a blessing–not a curse– when accompanied by regular exercise, healthful nutrition, not smoking, adequate sleep, social engagement and altruism, and a purpose in life.

Not only is exercise good for you, it burns calories! One loop of Central Park at a moderate pace — 6 miles — burns 743 calories: that’s five beers, two slices of pizza or, for energy, four pieces of rugelach.

I go to the gym about five times a week. I cross train: bodybuilding, intensive aerobics classes and stretching (Pilates and asthanga yoga). I feel and look better than I ever have. I’m also (not incidentally) a vegan. When people tell me, “I hope I have a body like yours at your age,” I tell them, “I wish you had a body like mine at YOUR age.”